This invention relates to automobile ignition systems, and more specifically, to a pulse generating unit for bypassing malfunctioning electronic components of an electronic ignition system. The unit supplies ignition pulses to the engine ignition coil to permit temporary engine operation and thereby allow the vehicle to be driven to a safe and convenient repair area.
The electronic ignition system is rapidly being accepted throughout the automobile industry as a modern and essentially maintenance-free replacement for the conventional mechanical ignition system. Such an electronic system typically comprises a magnetic pickup assembly coupled to a solid state electronic module which is in turn coupled to the primary winding of an engine ignition coil. The pickup assembly has a toothed armature, with one tooth for each engine cylinder, mounted for rotation about a distributor shaft and arranged to cyclically interrupt the magnetic field of a permanent magnet to induce a string of low voltage pulses in a pickup coil. The electronic module allows current to flow in the ignition coil primary winding upon receipt of each pulse from the pickup coil, and then cuts off that current upon termination of the pickup coil pulse to induce a high voltage pulse in the ignition coil secondary circuit for distribution to an engine spark plug.
Electronic ignition systems are highly advantageous over conventional mechanical ignition systems because of their replacement of mechanical switching components with electronic circuitry. More specifically, the magnetic pickup assembly and the electronic module contain no mechanical contact points to thus eliminate the conventional breaker points, rubbing block, etc. of a mechanical ignition system. As a result, the pickup assembly and the electronic module normally require little maintenance, and are thereby more long-lived than mechanical components. Further, the electronic components enable the generation of considerably higher sparking voltages than in a mechanical system to increase spark plug life and improve engine operating conditions.
Unfortunately, electronic ignition systems have not completely eliminated ignition system maintenance. Instead, electronic systems have presented the automobile industry with some new and perplexing maintenance problems. For example, while the pickup assembly and the electronic module of an electronic system are generally more long-lived than their mechanical counterparts, these electronic components do occasionally break down and fail to operate. In electronic systems, such failure is usually without any warning whatsoever, and renders the engine completely inoperable until the problem is solved or the malfunctioning component is replaced. In older mechanical systems, many causes of ignition failure could be temporarily remedied by simple "on the spot" adjustments of the mechanical ignition components which were almost always mounted in an easily accessible location. However, with modern electronic systems, the components are usually located in a substantially sealed distributor housing, and are thereby neither readily accessible nor easily adjustable. Further, the electronic module usually comprises microminiature circuitry and can be serviced only by complete replacement. All of this makes repair or replacement of the electronic ignition components an expensive and time-consuming task. Such repair simply cannot be safely or conveniently accomplished when the vehicle becomes disabled on a busy street, or during inclement weather. Accordingly, the vehicle operator is all too often obliged to incur the expense of having the vehicle towed to a safe, convenient repair location.
Some testing instruments are available for pinpointing ignition problems to the electronic components of the ignition system. These instruments can be electrically coupled to the magnetic pickup assembly, or to the electronic module, to indicate by means of a light or the like if the particular component is malfunctioning. Repair or replacement of the malfunctioning component, however, is still a time-consuming and intricate task which cannot be effectively performed on a vehicle stranded on a busy street or during foul weather. Towing of the vehicle to a safe repair location is still almost always required.
It is therefore desirable to provide an ignition unit for connection to an automobile's electronic ignition system, which bypasses the electronic ignition components, and which provides ignition pulses to allow at least temporary operation of the vehicle engine so that the vehicle can be driven to a safe repair area. Further, it is desirable to provide such an ignition bypass unit which is quickly and easily connected to the automobile ignition system, and which is both inexpensive to manufacture and compact in size.